Cataclysmic Variables from USNO-B1.0 Catalog: Stars with Outbursts on Infrared Palomar Plates

The search was performed for cataclysmic variable stars with outlying infrared magnitudes in USNO-B1.0 catalog. The selection was limited to objects in the Northern hemisphere with (B1-R1) 3.5. The search method is described, and the details on individual stars are given. In total 27 variable objects were found with 20 being the previously known ones and 7 - new discoveries. 4 of newly found variables are dwarf novae, while the remaining 3 - pulsating red variables of Mira or semi-regular types, including a heavily reddened one in Pelican nebula. The correct pulsation period is determined for two stars discovered by other researchers, and the dwarf nova nature is confirmed for another object previously suspected as such. The perspectives of the proposed search technique in the framework of Virtual Observatory are also discussed.Comment: 8 pages, 10 figures, submitted to Astronomy Letter

QZ Serpentis: A Dwarf Nova with a 2-Hour Orbital Period and an Anomalously Hot, Bright Secondary Star

We present spectroscopy and time-series photometry of the dwarf nova QZ Ser. The spectrum shows a rich absorption line spectrum of type K4 +- 2. K-type secondary stars are generally seen in dwarf novae with orbital periods P-orb around 6 h, but in QZ Ser the absorption radial velocities show an obvious modulation (semi-amplitude 207(5) km/s) at P-orb = 119.752(2) min, much shorter than typical for such a relatively warm and prominent secondary spectrum. The H-alpha emission-line velocity is modulated at the same period and roughly opposite phase. Time-series photometry shows flickering superposed on a modulation with two humps per orbit, consistent with ellipsoidal variation of the secondary's light. QZ Ser is a second example of a relatively short-period dwarf nova with a surprisingly warm secondary. Model calculations suggest that the secondary is strongly enhanced in helium, and had already undergone significant nuclear evolution when mass transfer began. Several sodium absorption features in the secondary spectrum are unusually strong, which may indicate that the present-day surface was the site of CNO-cycle hydrogen burning in the past.Comment: 11 pages, 3 postscript figures, 1 jpeg greyscale figure. Accepted for publication in PAS

Identification of new cataclysmic variables in the 1RXS and USNO-B1.0 catalogs

As a result of applying the original optical variability search method on publicly available data, we have found eight new cataclysmic variables and two possible Optically Violent Variable quasars among the previously unidentified X-ray sources in the ROSAT catalog. We describe the search method and present the characteristics of the newly identified variable stars. The obtained results demonstrate the large potential of the concept of Virtual Observatory for identifying new objects of astrophysical interest.Comment: 16 pages, 11 figures, 2 tables; submitted to Astronomy Letter

Spectrophotometric determination of phenolic compounds sum in plants using aluminum chloride, 18-molybdodiphosphate and Folin-Ciocalteu reagents

На основании результатов анализа ряда лекарственных препаратов на основе растительного сырья (таблетки, настойки, сиропы), лекарственных растений, фруктов, чаев и т.п. установлено, что 18-молибдофосфорный ГПК структуры Доусона (18-МФК), как и реактив Фолина-Чокальтеу (ФЧ), пригоден для спектрофотометрического определения суммы фенольных соединений. Этот вывод подтверждается высокой степенью корреляции ( R ² > 0.95) между данными, полученными двумя методиками. Результаты анализа обеими методиками во многих случаях практически не отличаются по абсолютной величине, что свидетельствует о близости кажущихся молярных коэффициентов, рассчитанных для реакций фенольных соединений с указанными реагентами. В случае, если общее содержание полифенолов определяется присутствием флавонолов или оксикоричных кислот, то взаимодействие последних с 18-МФК является быстрым и полным при проведении реакции при рН = 7.4. Для определения менее реакционноспособных фенольных соединений (полимерные полифенолы, катехины, оксибензойные кислоты) оптимальной является область рН выше 9.0. Корреляция результатов определения суммы полифенолов, полученных с использованием 18-МФК или реактива ФЧ, с результатами методики, использующей хлорид алюминия, наблюдается только в том случае, если в растениях преобладают флавоны, имеющие гидроксильные группы в положении 3 и/или 5.It was concluded from the results of the analysis of a number of drugs on the basis of vegetable raw materials such as tablets, tinctures, syrups, medicinal plants, fruits, teas, etc., that 18-molybdodiphosphate heteropoly anion (18-MPA) and Folin-Ciocalteu (FCR) reagents were suitable for the spectrophotometric determination of the total content of phenolic compounds. This conclusion was confirmed by a high degree of correlation ( R ² > 0,95) between the results obtained by the two methods. In many cases, the absolute difference between the results of both methods was low, and that was an evidence of closeness of apparent molar absorptivity values calculated for the reactions with the above mentioned reagents. Interaction of polyphenols with 18-MPA at pH 7.4 was rapid and complete when the total content of polyphenols was determined by the presence of flavonols or cinnamic acids. Range of pH > 9.0 was optimal for the determination of less reactive compounds (polymeric polyphenols, catechins, oxybenzoic acids). The results of the polyphenols sum determination obtained with 18-MPA or FCR reagents correlated with the results obtained using the aluminium chloride method only in the case when flavons with hydroxy groups in the positions 3 and/or 5 were dominating phenol species present in the plants

Discovery of an unusual bright eclipsing binary with the longest known period: TYC 2505-672-1 / MASTER OT J095310.04+335352.8

We report on the MASTER Global Robotic Net discovery of an eclipsing binary, MASTER OT J095310.04+335352.8, previously known as unremarkable star TYC 2505-672-1, which displays extreme orbital parameters. The orbital period P=69.1 yr is more than 2.5 times longer than that of epsilon-Aurigae, which is the previous record holder. The light curve is characterized by an extremely deep total eclipse with a depth of more than 4.5 mag, which is symmetrically shaped and has a total duration of 3.5 yrs. The eclipse is essentially gray. The spectra acquired with the Russian 6 m BTA telescope both at minimum and maximum light mainly correspond to an M0-1III--type red giant, but the spectra taken at the bottom of eclipse show small traces of a sufficiently hot source. The observed properties of this system can be better explained as the red giant eclipsed by a large cloud (the disk) of small particles surrounding the invisible secondary companion.Comment: 8 figures, 9 pages, Astronomy and astrophysics in prin

Reaction features of 18-molibdodiphosphate and Folin-Ciocalteu reagent with phenolic compounds

Сравнительное исследование реакции взаимодействия 18-молибдофосфорного гетерополикомплекса (18-МФК) и реактива Фолина-Чокальтеу (ФЧ) с рядом представителей различных классов фенольных соединений свидетельствует о близости реакционной способности обоих реагентов, что позволяет использовать 18-МФК, наряду с реактивом ФЧ, для оценки общего содержания фенолов. Установлено, что 18-МФК является более активным окислителем по отношению к фенолам, вследствие чего в сравнении с реактивом ФЧ интервал оптимальных значений рН сдвинут в более кислую область, скорость реакции выше, а используемая концентрация реагента на порядок меньше. Обнаружено, что при использовании обоих реактивов и измерении оптической плотности в максимуме поглощения гетерополисини (ГПС) градуировочные зависимости являются нелинейными. Возможной причиной этого служит изменение состава и глубины восстановления гетерополикомплекса (ГПК) при изменении соотношения ГПК : фенол. В спектрах ГПС, получаемых при восстановлении 18-МФК, имеется изобестическая точка (λ = 900 нм), что позволило получать строго прямолинейные градуировочные зависимости. При использовании 18-МФК влияние восстанавливающих сахаров, простых фенолов, сульфит-ионов, витаминов и некоторых других соединений на результат определения фенольных соединений становится намного меньшим. На примере определения рутина и аскорбиновой кислоты при совместном присутствии показано, что только при использовании 18-МФК удается определять раздельно в смеси фенол и более активный восстановитель путем варьирования рН определения.The comparative investigation of a reaction between 18-molybdophosphate heteropoly complex (18-MPC) and Folin-Ciocalteu reagent (FCR) with a diversity of the representatives of different phenolic compounds classes shows a similar reaction behavior for both reagents. This evidence can be used for the application of 18-MPC along with FCR for the evaluation of total content of phenols. It was established that 18-MPC is more active as an oxidizing agent with respect to phenols and for this reason in comparison with FCR the range of optimal values of pH is displaced into the more acidic region, the reaction rate is higher, and the concentration of the reagent is one order of magnitude less. It was also discovered that by using both reagents and measuring the absorbance in absorption maximum of heteropoly blue (HPB), the graduation curves were nonlinear. The observed phenomenon was explained by the changes in the composition and depth of the HPB reduction occurring when changing the ratio between the heteropoly complex and the phenol. The isobestic point present in the absorption spectra of HPBs and which was acquired from 18-MPC allows obtaining strictly linear calibration curves. By using 18-MPC the influence of reducing sugars, simple monophenols, sulphite ions, vitamins and some other compounds on the result of the determination of phenolic compounds becomes much smaller. It was shown by example of the ascorbic acid and rutin determination in the mixture that only by using 18-MPC it was possible to determine phenol and more active reducing agent separately by varying the pH of the determination